Broadband step attenuator with improved time domain performance

Abstract

An integrated step attenuator (“ISA”) monolithically integrated on a single chip for adjusting an input signal. The ISA may include a step attenuation network (“SAN”) that may include at least one switchable attenuation section, and at least one electronically switchable trimming network (“ESTN”). The SAN may be configured to adjust the input signal responsive to the state of a switch that bridges the attenuation sections of the SAN, and the ESTN may be configured to adjust the input signal responsive to the state of a switch in signal communication with one or more shunt resistors in the ESTN.

Description

BACKGROUND OF THE INVENTION[0001]Fixed and step attenuators are used in a wide variety of applications for signal conditioning and level control. Specifically, attenuators may reduce signal levels, match impedances of sources and loads, and measure gain or loss of a two-port device. Step attenuators are widely used in electronic systems to control the amplitude of signals. Step attenuators, as opposed to fixed value attenuators, have attenuation values that may be selected by electronically or digitally controlled lines, and there may be one attenuation state or multiple attenuation states. They are usually made with resistors having fixed resistances that are connected by electrically controllable switches. The switches may be mechanical (e.g., microelectromechanical systems (“MEMS”) switches or traditional relays) or made with semiconductors (e.g., Field Effect Transistors (“FETs”)). These resistors are usually connected to form “Pi” (see FIG. 1A) or “T” attenuators (see FIG. 1B),...

AI Technical Summary

Benefits of technology

The ISA improves the accuracy and tolerance of impedance match, maintains constant attenuation step size, and enhances group delay flatness at higher frequencies, reducing complexity and cost while minimizing signal loss.

Problems solved by technology

Therefore, in an IC type of switch, there is a manufacturing tolerance for the impedances and the resulting variation in the impedances values and the Ron of the IC switch generally limits the accuracy of the attenuator match.

Unfortunately, this adds to the cost of the attenuator.

Unfortunately, both these approaches add cost and complexity to the attenuator assembly.

Unfortunately, while these shunt-capacitor low pass filters are effective in extending the bandwidth over which the attenuation is constant, they usually increase the minimum attenuation and add complexity to the design and implementation of the attenuator assembly.

Images